Manufacture of asphalt



Patented Dec. 10, 1935 UNITED STATES PATENT OFFICE.

MANUFACTURE OF ASPHALT Felton S. Dengler, Earl W. Gardner, and Dudley H. Felder, Port Neches, Tex., assignors to The Texas Company, New York, N. Y., a corporation of Delaware No Drawing. Application February 23, 1932,

' Serial No. 594,740

'1 Claims. (01. 196-44) This invention relates to the treatment of asphaltic products and relates particularly tothe stabilization and homogenization of residues derived from the thermal conversion of petroleum hydrocarbons for the preparation of asphaltic products.

An important object of the invention is to stabilize and homogenize cracked residuum derived from the pyrolytic cracking of petroleum hydrocarbons to prevent separation and segregation of their components and to inhibit the formation of compounds which tend to separate from the cracked residuum, and to render homogeneous the residuum and the asphaltic products pre- 5 pared therefrom.

Residua suitable for treatment, according to the invention may comprise residual fractions resulting from the pyrolytic cracking of mineral oils wherein the oil is subjected to heat treatment in either the vapor or liquid phase andusually under pressures substantially above atmospheric. The heavy tar or pitch product resulting from this type of cracking operation is quite generally known in the industry as cracked residuum, and as a matter of convenience will be referred to hereinafter as such. v

The cracked residuum referred to, normally contains unstable, CCh isoluble hydrocarbon constituents as distinguished from CS: insoluble 3o constituents or free carbon. Unless stabilized,

the unstable constituents form-additlonal insoluble compounds which tend to separate or segregate within the tar, thereby rendering it unsuitable for the manufacture of asphalt.

35 In accordance with the present invention a heterogeneous residuum containing unstable and insoluble constituents is subjected to a novel treatment, as set forth more particularly hereinafter, to dissolve the insoluble constituents and 40 stabilize the unstable components to produce a homogeneous and stable material. The insoluble hydrocarbon constituents of the heterogeneous mixture, by this treatment, are rendered soluble in CC14, a property which has beenfound to im- 45 prove the quality of the material to the extent that it is possible to manufacture commercial asphalt or other desirable asphaltic products from the resulting homogenized mixture or has material.

50 The unstable hydrocarbon constituents, such as those soluble in CS2 but insoluble in G014, have been found to be unsuitable for incorporating in asphalt. For example, in the treatment of cracked residuum according to established meth- 55 ods, which are generally used for the production of asphalt from uncracked petroleum residue or asphaltic residue, such as steam reduction or all blowing at elevated temperatures, there is not only a notable increasein the amountof CS2 insolubles, such as carbon or coke, but also of 5 the C014 insolubles and CS2 solubles, commonly known as carbene constituents; The increase of these materials is probably due to a change of form of the'unstable hydrocarbon constituents of the cracked residuum which is often evidenced 10 by an increase in the carbene content when the cracked residuum is merely stored in tankage over a period of time.

More particularly, according to the present invention, the stabilization of the unstable hydro- 15 carbon constituents of the cracked residuum is advantageously accomplished by mixing a stabilizing agent with the cracked residuum. While it is contemplated that other stabilizing agents may be used, it is preferable to use a hydrocarbon 2o material which possesses a relatively high asphaltene content. V

Hydrocarbons suitable for use as stabilizing agents may comprise natural asphalts or asphalt products derived from crude petroleum which 25 have not been subjected to substantial or appreciable cracking. Materials derived from pctroleum that have been found to be useful, according to the invention, may include residues from asphalt base petroleum; residues from semiasphaltic and non-asphaltic base petroleum; oxidized residues; and solid orsemi-solid asphalts. Many uncracked petroleum residues have sufficient natural solvent properties to dissolve most of the C014 insoluble hydrocarbons present in cracked residue while in others it is occasionally necessary to air blow the uncracke'd residue, so as to increase its value as a solvent and stabilizer or homogenizer, The foregoing materials when mixed with cracked residuum have been 40 found to possess peculiar solvent or stabilizing properties for unstable constituents, and may be used as homogenizing agents under appropriate conditions to effect the desired conversion of the cracked residuum into base material suitable for the manufacture of fuel oil, road oil or asphaltic products. l

The mixing of the cracked'residuum and petroleum residue or other stabilizing agent may be carriedout with various modifications depending to some extent on the nature of the materials treated. In some cases, the cracked residuum may advantageously be thinned down with naphtha or other low boiling material for, the V purpose of'reducing its viscosity and facilitating 56 more complete mixing with the asphaltic or uncracked residue and after mixing, the thinner may be removed by evaporation or distillation. Also, the temperature at which the mixing of the cracked residuum and stabilizing material is carried out may be varied to whatever extent necessary to effect the desired results, though the maximum temperature employed will probably not be greatly in excess of about 600 F. in order to avoid exposing the mixture to cracking conditions.

The following examples are given for purposes of illustration to show the application of the invention to the treatment of certain materials. In the examples the C014 solubilities of the residues and mixtures areall based on the amount soluble in CS: as being 100%, while the CS: and 86 B. naphtha solubilities are based on the total original sample. In other words, the solubility tests, exceptthe 86 naphtha, were made in accordance with A. S. T. M. methods 10165-27 and D4--27.

Equal parts of cracked residuum having a specific gravity of 1.065 and a furol viscosity at 210 F. of 33 seconds, and an uncracked residue from Mexican petroleum with a softening point of 102 F. were mixed and the mixture was heated to about 240 F. The solubility of the cracked residuum in C014 was increased from about 94% to 99.6%. The product, by blowing with air or by reducing with steam, produced excellent asphalts suitable for different classes of road oils and binders.

Equal parts of a cracked residuum which had been steam distilled to 400 F. flash (Cleveland open cup) and a mixture of asphaltic residues from Mexican and Venezuela petroleum were heated to the order of 400 F. and mixed by agitating with air. The solubilities ofthe resulting product in CS2. and C014 were approximately 99.8% and 100% respectively. A quantity of the latter material, charged to a conventional converter for producing air blown asphalt, was heated to about 450 F. and blown to a softening point of 229 F.A. S. T. M. ring and ball method No. D36-26. The final hard asphalt was 99.8% soluble in CS: and 99.8% soluble in C014, whereasv the cracked residuum alone treated in a similar manner without stabilization produced an asphalt of the same melting point but only about 90% soluble in C014. v 1

While in the foregoing examples, the stabilizing material has been mixed with the cracked residuum and the mixture then subjected to steam reduction or air-blowing to produce a desired product, it has also been found advantageous to first subject the cracked residuum to conversion by steam reduction or air blowing or both, and then mix the stabilizing agent with the resulting converted residuum'to produce a final product of desired properties. The finished asphalt may be further steam reduced or air blown, or both, as necessary to meet specifications.

The proportions of the stabilizing agent and the material to be stabilized will necessarily vary within rather broad limits due to the nature of the stabilizer and the quantity of unstable constituents in the cracked residuum or other unstable material. The materials under treatment, for example, may range in consistency from liquids to fairly hard solids and it is obvious that the consistency of each substance has an important bearing on the ease of stabilization; thus, the concentration of unstable constituents per unit volume of unstable material and the percentage of effective stabilizing constituents in a given stabilizer are important factors. The percentage of stabilizer required, however, has been found in most cases to be inversely proportional to the as-' phaltenes present in the stabilizer which, as occurring naturally, depends on the source of the particular sample. As previously mentioned, however, the eifectiveness of the residue as a stabilizer may be increased by preliminarily treating it, as by air blowing, and the increase in effectiveness will be generally proportional to the inm crease of the asphaltenes content. It is usually desirable to use a stabilizing material containing 3%-40% asphaltenes and in such instance the amount of stabilizer required may vary from 20% of the total volume of the mixture. 15

Obviously many modifications and variations of the invention, as hereinbefore set forth, may be made without departing from the spirit and scope thereof, .and therefore only such limitations should be imposed as are indicated in the append- 20 ed claims.

We claim:

1. The process of manufacturing a stable homogeneous asphalt base substantially completely soluble in carbon tetrachloride fromcracked re- 35 siduum formed in the thermal conversion of mineral oil and which is relatively high in unstable tetrachloride insoluble compounds comprising heating the residuum and blowing with air to remove its volatile low boiling constituents to in- 3b crease its hardness and raise its melting point, and mixing therewith an air-blown, substantially uncracked asphaltic residue adapted to stabilize the unstable carbon tetrachloride insoluble compounds in the cracked residuum and to inhibit as their formation and segregation.

2. The process of manufacturing a stable homogeneous asphalt base substantially completely soluble in carbon tetrachloride from cracked residuum formed in the thermal conversion of mineral oil and which is relatively high in unstable carbon tetrachloride insoluble compounds comprising reducing the residuum by heating and steaming to remove its volatile low boiling constituents, blowing with air a petroleum residue produced at less than cracking temperature and pressure, to thereby adapt it for stabilising unstable. carbon tetrachloride insoluble compounds and for inhibiting the formation and separation of insoluble cracked residuum compo-' nents, mixing the cracked residuum with the air blown residue and air blowing the mixture at elevated temperature to effect complete mixing and stabilization.

3. The process of manufactm'ing a stable homo- 55 geneous asphalt product at least 99% soluble in carbon tetrachloride from cracked residuum formed in the thermal conversion of mineral oil and which is relatively high in unstable carbon tetrachloride insoluble compounds comprising 60 mixing with the residuum a substantially uncracked asphaltic residue, which has been airblown to increase the asphaltene content, adapted to stabilize the unstable carbon tetrachloride insoluble compounds and to inhibit the formation. .55 separation or segregation of insoluble cracked residuum components, and air blowing the stabilized homogenized mixture at an elevated temperature, not in excess of about 600 I". to produce a product of desired consistency.

4. The method of homogenizing and stabilizing a heterogeneous unstable cracked petroleum residue whichis relatively high in unstable carbon tetrachloride insoluble compounds which com prises admixing therewith an air-blown substan- 1 tially uncracked petroleum residuum constituting from 20% to 80% of the mixture and air-blowing said mixture at elevated temperatures.

5. A stable homogeneous asphalt composition formed of 80-20% cracked residuum which has been reduced without oxidation to a relatively low penetration and which is relatively high in unstable constituents tending to separation and segregation of the component parts, and 20-80% of a hydrocarbon stabilizing agent comprising air blown substantially uncracked petroleum distillation residuum, characterized by having a relatively high asphaltene content, sufllcient to render the unstable constituents of said cracked residuum stable on storage.

6. The process of manufacturing a stable homogeneous asphalt product at least 99% soluble in carbon tetrachloride from cracked residuum formed in the thermal conversion of mineral oil and which is more than 3% insoluble in carbon tetrachloride, comprising air blowing a substantially uncracked asphaltic residue to increase the an air blown substantially uncracked petroleum 15 residuum to homogenize and stabilize the cracked residue and to render said residue over 99% soluble in carbon tetrachloride.

FELTON S. DENGLER. EARL W. GARDNER. DUDLEY H. FELDER. 

